Bohm is the starting first baseman at this point (plus he's actually got reverse splits this year). I think this was Sosa's first game off in a week (since he was injured), and there won't be a DH spot for Bohm (as he had so Clemens could play 1B on Thursday) once Harper is back either. They can ride it out (for Hall too) because there are no LHB options otherwise. Also they can ride it out because the team's record since the first six games says they can.
And I suspect that once Harper is cleared to slide he won't be that far off from making short infield throws.